The purpose of the research is to examine the relationship between psychopathology and regional brain function. The specific aims are to determine the pattern of regional brain dysfunction manifested in measures of physiologic activity, obtain measures of brain anatomy, and integrate these data with clinical and neuropsychological assessment. Two major forms of severe psychopathology were selected: schizophrenia and depression. The physiologic measures will be regional cerebral blood flow (rCBF), obtained with the Xenon Xe 133 inhalation technique, local cerebral glucose metabolism (1CMRgl), local cerebral oxygen metabolism (1CMR02) and local cerebral blood flow (1CBF) determined by positron emission tomography (PET). Additional physiological measures to be phased into the research are phosphorus nuclear magnetic resonance spectroscopy (31-P NMR), single photon emission computerized tomography (SPECT) and brain electric activity mapping (BEAM). Neuropsychological functioning will be assessed with a standardized battery which measures receptive and expressive aspects of cognition and affect and provides computerized topographic images. Patients will be studied in the acute state and after treatment to enable the establishment of the relationship between clinical status and regional brain function. Brain anatomy will be imaged with computerized tomography (CT) and proton magnetic resonance imaging (MRI).